1. Field of the Invention
This invention relates to the field of flexible pipe having multiple, reinforcing layers.
2. Description of the Related Art
Flexible multilayer pipe is known in the art. However, existing multilayer pipes have significant disadvantages. Pipes that have multiple helically wound layers are generally bonded to the core. The bonding reduces flexibility of the pipe and it causes the individual layers to separate from the core as the pipe is repeatedly flexed. To improve flexibility, helical wrapped layers can be used that are not bonded to the core. Attempts have been made to helically wrap multiple unbonded layers of steel strips over a core. For example, see U.S. Pat. No. 6,705,351. In such a configuration, gaps are needed between successive wraps of the steel strips to allow the pipe to flex. Tabs or welds or other means are necessary in such a configuration to be sure that gaps will exist between wraps. Also, the use of steel in such a configuration is both heavy and expensive.
What is needed is a flexible multi-layer pipe that is lightweight, inexpensive and flexible. The resulting pipe should not need tabs or welds between wraps of the strips.